Conventional coaxial cable typically consists of a centrally located inner electrical conductor surrounded by and spaced inwardly from an outer cylindrical electrical conductor. The inner and outer conductors are separated by a dielectric insulating sleeve, and the outer conductor is encased within a protective dielectric jacket. The outer conductor can comprise a sheath of fine braided metallic strands, a metallic foil, or multiple layer combinations of either or both.
Conventional coaxial cable connectors typically include an inner cylindrical post configured for insertion into a suitably prepared end of the cable between the dielectric insulating sleeve and the outer conductor, an end portion of the latter having been exposed and folded back over the outer dielectric jacket. The inner conductor and the dielectric insulating sleeve thus comprise a central core portion of the cable received axially in the inner post, whereas the outer conductor and dielectric jacket comprise an annular outer portion of the cable surrounding the inner post. An example may be seen in U.S. Pat. No. 5,470,257 (Szegda).
Conventional coaxial cable connectors further include an outer component designed to coact with the inner post in securely and sealingly clamping the annular outer portion of the cable therebetween. In “crimp type” connectors, as disclosed in U.S. Pat. No. 5,073,129 (Szegda), the outer component comprises a sleeve fixed in relation to and designed to be deformed radially inwardly towards the inner post. In “radial compression type” connectors, as disclosed in U.S. Pat. No. 5,470,257 (Szegda), the outer component comprises a substantially non-deformable sleeve adapted to be shifted axially with respect to the inner post into a clamped position coacting with the inner post to clamp the prepared cable end therebetween.
Because coaxial cable connectors consist of multiple parts, water and/or water vapor are able to penetrate through small holes in the connector created between the inner portion and outer portion of the connector as well as between the connector and the coaxial cable. The introduction of water and/or water vapor to the inside of a coaxial cable connector can cause destruction of the inside of the coaxial cable connector resulting in lower performance and the eventual need to replace the connector. Similarly, other corrosive vapors can cause destruction by entering the coaxial cable connector through tiny holes between the inner and outer portions of the connector as well as between the connector and the coaxial cable.
In the past, attempts have been made to fix this problem by injecting materials into the connectors to fill these small holes and prevent moisture from entering the coaxial cable connectors. In U.S. Pat. No. 3,654,577 (Spinner et al), an attempt to address this problem was made by injecting the hollow portions of a waveguide terminator with a viscous elastic material to prevent the moisture from entering the terminator through its outer surfaces tiny holes. U.S. Pat. No. 3,818,120 (Spinner) also addressed this problem using the injection method to prevent moisture from entering a coaxial plug connector by filling the holes of the outer surface with a self-curing synthetic resin. Finally, U.S. Pat. No. 5,510,405 (Heucher et al) addressed this problem by injecting a hot-melt type adhesive into coaxial cable connectors to seal the connector and prevent moisture from entering.
These injection methods have been successful in preventing moisture damage, however they have also created additional problems within the connectors. One such problem is the inability to control where the injected material goes once inside the connector, thereby damaging other components of the connector. In addition the injected material could seep out of other holes in the connectors and create problems for the installer. The injection method also makes installation more difficult because it requires the installer to use additional materials and tools to perform the installation. Difficult installation is unfavorable because coaxial cable connectors are often installed in towers located high off the ground.
Another method used in the past to prevent moisture from entering connectors involves protection of the inner pin of the connector from inside of the connector body. In U.S. Pat. No. 4,299,434 (Ishikawa), an attempt was made to address the moisture problem in connectors by mounting elastomeric layers within a watertight RF coaxial jack connector. The elastomeric layers were mounted within the connector body to protect the split pin, thus protecting against destruction of the connector. This method could still result in moisture coming into contact with the pin and destroying the connector if there were any deformities in the elastomeric layers. Even the slightest crack or hole would be enough to enable water to enter the connector and cause damage. In addition, this method requires additional components to be manufactured as well as an additional step in the assembly process, resulting in a more expensive connector.
Attempts have also been made to solve the moisture problem by placing bonding materials onto the different components of connectors just prior to installation, which react during installation to create a moisture seal. In U.S. Pat. No. 6,148,513 (Schiefer et al), a sealing material is placed on at least two components of the connector prior to installation, whereupon the sealing material reacts causing its volume to enlarge and fill the hollow spaces between the contact part and conductor and the contact part and the sheath during installation. The sealing material creates a moisture barrier to prevent damage to the connector. As with some of the other methods of creating a moisture seal, this method also requires that the installer apply the sealing materials just prior to installation. This requires the installer to carry extra materials and tools with him/her and makes the installation process more difficult.
Finally, others have attempted to solve the moisture problem in electrical connectors using microcapsules containing an adhesive solution. In U.S. Pat. No. 5,941,736 (Murakami), a microcapsule layer containing an adhesive solution is used to create a liquid tight seal within electrical wire connectors. Upon rupture of this microcapsule layer the adhesive solution is released and enables the housing and connection terminals of the connector to be joined and form a liquid tight seal. The adhesive solution is used to prevent oil from leaking out into the rest of the connector body.
The present invention utilizes microencapsulation adhesives. Typical microencapsulation adhesives are seen in U.S. Pat. No. 4,536,524 (Hart et al) and U.S. Pat. No. 4,940,852 (Chernack). The '524 patent is for a microencapsulated epoxy adhesive system which can be used to form an adhesive bond between two components. The '852 patent is for a liquid microencapsulated adhesive layer which can also be used to join two components. A microencapsulated adhesive is envisioned for the present invention to form the adhesive seal and locking action between the defined components of the coaxial cable connector. The make up of the adhesive prevents moisture both in liquid and vapor form from entering the coaxial cable connector.
Accordingly, a new way to keep liquids and moisture out of coaxial cable connectors while simultaneously developing a mechanical seal to inseparably lock the connector components is necessary to reduce the frequency of connector replacement and to reduce the costs and labor involved with the current methods of creating moisture seals for coaxial cable connectors. An adhesive layer is pre-applied to defined components of the coaxial cable connector in their pre-assembled configuration to avoid increased labor for the connector installer and to ensure a minimal but uniform layer of the microencapsulated adhesive is present on the desired connector components.